A combustion engine exhibits irregularities due to the combustion events occurring sequentially in the engine's cylinders, the frequency of the irregularities varying in particular as a function of the number of cylinders and the rotation speed of the engine. The function of a damping system is to filter the vibrations caused by the irregularities upstream from the gearbox. Otherwise vibrations would enter the gearbox and produce particularly undesirable noise, impacts, and acoustic emissions therein during operation.
Damping systems of the pendulum type, also called “pendulum oscillators” or “pendulums,” which are installed in motor vehicle transmissions, are known in the existing art.
One such damping system of the pendulum oscillator type is described, for example, in the document FR 2989753. The damping system has a support member and a plurality of pendulum flyweights mounted oscillatingly with respect to the support member. Each pendulum flyweight is mounted oscillatingly with respect to the support member by means of two rolling bodies that each interact on the one hand with an inner raceway carried by said pendulum flyweight, and on the other hand with an outer raceway facing said inner raceway and carried by the support member.
In a damping system of this kind, the outer raceways are formed in orifices configured in the support member in such a way that the angular deflection of the pendulum flyweights with respect to the support member is necessarily limited. In certain operating conditions, and in particular upon engine starting, the amplitude of the vibrations is such that the pendulum oscillator is saturated and the pendulum flyweights come into abutment against the support member. These operating conditions result, each time, in impacts between the pendulum flyweights and the support member. In order to limit acoustic emissions under such operating conditions, the support member and/or the pendulum flyweights are equipped with abutment elements made of elastomer which limit the deflection of the pendulum flyweights with respect to the support member. Elastomer abutment elements of this kind are subjected, however, to high temperatures and to a large number of impacts. Elastomer abutment elements of this kind thus result in a limitation of the service life of the damping system, and in an increase in the system's cost and complexity.